.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
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.\" %%%LICENSE_END
.\"
.\" References consulted:
.\"     Linux libc source code
.\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
.\"     386BSD man pages
.\" Modified Sat Jul 24 19:17:53 1993 by Rik Faith (faith@cs.unc.edu)
.TH GETUSERSHELL 3  2016-03-15 "GNU" "Linux Programmer's Manual"
.SH NAME
getusershell, setusershell, endusershell \- get permitted user shells
.SH SYNOPSIS
.nf
.B #include <unistd.h>
.sp
.B char *getusershell(void);
.sp
.B void setusershell(void);
.sp
.B void endusershell(void);
.fi
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR getusershell (),
.BR setusershell (),
.BR endusershell ():
.nf
    Since glibc 2.21:
.\"             commit 266865c0e7b79d4196e2cc393693463f03c90bd8
        _DEFAULT_SOURCE
    In glibc 2.19 and 2.20:
        _DEFAULT_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
    Up to and including glibc 2.19:
        _BSD_SOURCE || (_XOPEN_SOURCE && _XOPEN_SOURCE\ <\ 500)
.fi
.ad b
.SH DESCRIPTION
The
.BR getusershell ()
function returns the next line from the file
.IR /etc/shells ,
opening the file if necessary.
The line should contain
the pathname of a valid user shell.
If
.I /etc/shells
does not exist or
is unreadable,
.BR getusershell ()
behaves as if
.I /bin/sh
and
.I /bin/csh
were listed in the file.
.PP
The
.BR setusershell ()
function rewinds
.IR /etc/shells .
.PP
The
.BR endusershell ()
function closes
.IR /etc/shells .
.SH RETURN VALUE
The
.BR getusershell ()
function returns NULL on end-of-file.
.SH FILES
.nf
/etc/shells
.fi
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbw31 lb lb
l l l.
Interface	Attribute	Value
T{
.BR getusershell (),
.BR setusershell (),
.br
.BR endusershell ()
T}	Thread safety	MT-Unsafe
.TE
.SH CONFORMING TO
4.3BSD.
.SH SEE ALSO
.BR shells (5)
